The development of offshore oil fields in deep waters has necessitated the laying of lengthy pipelines in order to transport oil and gas from remotely located fields to more centrally located production and storage facilities. In the past, this has been accomplished by towing sections of the pipeline to the location at which the pipeline is to be submerged. Buoyant modules are sometimes attached to the pipeline to reduce frictional stresses between the pipeline and the sea floor. More recently it has been suggested to provide a sufficient number of buoyant modules to make the pipeline positively buoyant and to attach to each module a chain that would partially drag on the sea floor to maintain the pipeline at a predetermined distance above the sea floor.
After the pipeline has been installed, the buoyant modules must be removed. If the modules have been submerged to a depth below which it is no longer cost-effective to use a diver, approximately 200 to 300 feet, remotely controlled apparatus must be used to release each module from the pipeline. This has been accomplished by any one of a number of latching mechanisms which can be mechanically, hydraulically, electrically or pyrotechnically actuated to release each module. Remote control has also been used with apparatus for severing a strap that binds a buoyant module to the pipeline. Frequently, however, such mechanisms are susceptible to unforeseen openings which can cause extensive damage to the pipeline. For example, if one or more modules were accidently released, the weight of the pipeline between the remaining modules could cause the pipeline to buckle. Such mechanisms are also susceptible to unforeseen jamming when the buoyant module is to be released. When jamming occurs at this depth, the buoyant module can only be released by using extremely costly techniques such as atmospheric diving systems or deep saturation diving.